Unsure of Formula to Use- IF function?

Hi good afternoon,

I need help with a basic formula, well at least I think it's basic.

I Have a sheet in excel with 2 values, one is a text and one is a long string of numbers and letters, it looks like this:

A1: ABC Company, Inc
B1: 800610000000Xfo

On my second sheet, I have to match up the long string of numbers/letters with the corresponding Company name from the first sheet. Basically, ABC Company, Inc appears on both sheets, but I need the string of numbers and letters to appear next to it if it appears.

IF Sheet2 A4= ABC Company, Inc, THEN I need 800610000000Xfo to appear in that cell.

Does anyone know how to do this!? thank you in advance for your help.